Add section on buffer protocol support

Author: jakirkham

_posts/2019-05-02-zarr-2.3-release.md

@@ -138,6 +138,22 @@ adapter](https://zarr.readthedocs.io/en/stable/api/n5.html#zarr.n5.N5Store)
 which allows reading and writing of data on disk in the N5
 format. 
 
+## Support of the buffer protocol
+
+The Python buffer protocol for those that are familiar is a specification for
+how to share large blocks of memory between different libraries without
+copying. This protocol has evolved over time from its original introduction in
+Python 2 and later revamped implementation added in Python 3 (with backports to
+Python 2.6 and 2.7). Due to the changes in its behavior from Python 2 to Python
+3 and what objects supported which parts of the buffer protocol, it was a bit
+challenging to leverage effectively in Zarr. This despite the value of having
+zero-copy when storing data or performing filtering and compression.
+
+Thanks to some under-the-hood changes in Numcodecs 0.6.0 and Zarr 2.3, the
+buffer protocol is now cleanly supported for Python 2/3 in both libraries when
+working with data. In addition to improved memory handling and performance,
+this should make it easier for users developing their own stores, compressors,
+and filters to use with Zarr.
 
 ## Future developments